DE102007060669A1 - Tandem time-of-flight mass spectrometer for quantitative and qualitative analysis of traces of compounds and also for structural analysis of sample ions, comprises detector for detecting ions - Google Patents

Abstract

The tandem time-of-flight mass spectrometer comprises a time-of-flight mass spectrometer (TOF-MS) with a spiral flight path and another reflectron-type TOF-MS for analyzing masses of the fragmented ions. A detector (20) is provided for detecting the ions, which passes through the latter TOF-MS. The former TOF-MS with each circulation of the ions on the spiral flight path satisfies spatial focusing conditions concerning a flight direction and a level standing perpendicularly to the flight direction. An ion gate (16) is arranged on the spiral flight path of the former TOF-MS. An independent claim is also included for a method for tandem time-of-flight mass spectrometry.

Description

Background of the invention

1. Technical field of the invention

The The present invention relates to a device as well Tandem time-of-flight mass spectrometry method used for quantitative analysis Analysis and simultaneous qualitative analysis of traces of compounds and for structural analysis of sample ions.

2. Description of the Related Art

(Mass spectrometry)

One Mass spectrometer ionizes a sample in an ion source, separating the ions according to the respective m / z-value (mass-charge-ratio) through the mass analyzer and detects the separated ions by means of a detector. The result is in the form of a mass spectrum in which the m / z value is plotted on the horizontal axis is while the relative amount is on the vertical axis is offered. The m / z values and the relative intensities the compounds contained in the sample are detected. It can qualitative and quantitative information about the sample be derived. As ionization method, mass separation method and ion detection methods, various methods are used. The present invention is particularly close to bulk separation connected. Depending on the different principles of Mass separation will be mass spectrometer in quadrupole mass spectrometer (QMS), Ion Trap Mass Spectrometer (ITMS), Magnetic Sector Mass Spectrometer, Time-of-flight mass spectrometer (TOFMS) and ion cyclotron resonance mass spectrometer divided by Fourier transform (FTICRMS).

(MS / MS measurement and MS / MS device)

In a mass spectrometer, the ions generated in the ion source in the mass analyzer are separated according to the respective m / z value and the separated ions are detected. The result is represented in the form of a mass spectrum in which the m / z values of the ions and their relative amounts are graphically represented. In contrast to the MS / MS measurement described later, this measurement is referred to below as MS measurement. In an MS / MS measurement, certain ions generated in the ion source are selected by the first stage of the mass spectrometer (abbreviated as MS1). The selected ions are called precursor ions and can spontaneously decay or become fragmented. The resulting product ions are mass analyzed in the later stage MS mass spectrometer (hereafter abbreviated as MS2). A device that enables such an MS / MS measurement is called an MS / MS device ( 1 ).

In an MS / MS measurement one obtains the m / z values of the precursor ions, the m / z values of the product ions, which are generated by different fragmentation paths, as well as information about their relative intensities. Consequently, structural information about the precursor ions can be derived ( 2 ). There are several variations of the aforementioned combination of two mass spectrometers as MS / MS devices that can perform MS / MS measurements. Furthermore, there are many fragmentation methods including collision-induced dissociation (CID) using collisions with gas, photodissociation, and electron capture or electron transfer. The device related to the present invention is an MS / MS device having two TOF-MS devices connected in tandem. Between the two TOF-MS devices a device for a CID-based fragmentation is arranged. Usually this system is called TOF / TOF.

The from an MS / MS device using a CID method derived fragmentation information differs depending on of different collision energies, that is, of different ones kinetic energies of the ions entering the collision cell. In the case of the MS / MS devices used here the energies in low energy CID in the range of some ten eV and high energy CID ranging from several kV to several tens of kV divided.

The difference is determined by the instrumental structure. This is summarized in Table 1. Table 1 MS1 MS2 collision energy QMS QMS Low QMS TOFMS Low TOFMS TOFMS High Magnetic sector MS Magnetic sector MS High Magnetic sector MS QMS Low Ion trap MS Ion trap MS Low Ion trap MS TOFMS Low FTICR MS FTICR MS Low

One The advantage of the high-energy CID is that it can be used in fragmentation of peptides that contain tens of amino acids with each other concatenated, get information about side chains can. It can be between leucine and isoleucine, which have the same molecular weight have to be distinguished.

(Time of Flight Mass Spectrometer (TOFMS))

wobei m die Masse des Ions, q die elektrische Ladung des Ions und e die Elementarladung sind.A TOFMS is a mass spectrometer for determining the mass-to-charge ratios of ions by imparting a constant amount of energy to the ions so that the ions are accelerated and caused to move, with mass-to-charge ratios The times at which the ions arrive at the detector, determined. In TOFMS, the ions are accelerated at a constant, pulsed voltage V _a . At this point in time, the law of conservation of energy results in the speed of the respective ion

where m is the mass of the ion, q the electric charge of the ion and e the elementary charge.

The Ion reaches the backward in a certain way Distance L arranged detector after a flight time T.

Formula (3) indicates that the time of flight T changes as a function of the mass m of the ion. A device for separating masses using this principle is a TOFMS. An example of a linear TOFMS is in 1 shown. In addition, reflectron TOF-MS devices which achieve improvements in energy focusing and extension of the flight path by placing a reflectron field between an ion source and a detector are widely used. An example of a reflectron TOFMS is in 4 shown.

(TOFMS with helical trajectory)

definiert, wobei T die gesamte Flugzeit und ΔT die Peakbreite darstellen. Das heißt, dass die Massenauflösung verbessert werden kann, wenn die gesamte Flugzeit T verlängert werden kann, während man die Peakbreite ΔT konstant hält. Jedoch führt in dem linearen TOFMS und dem Refklektron-TOFMS nach dem Stand der Technik eine Verlängerung der gesamten Flugzeit T, das heißt eine Verlängerung der gesamten Flugstrecke, unmittelbar zu einer Vergrößerung des Geräts.The mass resolution capability of a TOFMS device is known as

where T is the total time of flight and ΔT is the peak width. That is, the mass resolution can be improved if the total flying time T can be prolonged while keeping the peak width ΔT constant. However, in the prior art linear TOFMS and refectory TOFMS, extending the total time of flight T, that is, extending the total flight distance, directly results in enlargement of the device.

A multi-turn time-of-flight mass spectrometer is a device designed to achieve high mass resolution while avoiding bulkiness of the device. M. Toyoda, D. Okumura, M. Ishihara and I. Katakuse, J. Mass Spectrom., 2003, 38, pp. 1125-1142 ). This device uses four toroidal electric fields, each of which combines Matsuda plates with a cylindrical electric field. The ions are caused to make several rounds on an 8-shaped trajectory. Consequently, the total flight time T can be extended. This device makes it possible to maintain the spatial and temporal distribution at the detection surface up to the first-order term.

however suffers the TOFMS, which causes the ions to to make several rounds of a closed orbit on a passing problem. That means that ions with small m / z and high speeds ions with big m / z and lower speeds, because the ions make several rounds on a closed trajectory carry out. Consequently, the fundamental concept of a TOFMS, therefore lighter ions earlier at the detection surface arrive, no more.

To solve this problem, a helical ion trajectory TOFMS has been developed. The TOFMS with a spiral trajectory is characterized in that the starting point and the end point of the closed trajectory with respect to the plane of the closed trajectory are shifted in the orthogonal direction to each other. This is achieved by a process in which the ions enter obliquely from the beginning (cf. JP-A-2000-243345 ) by a method in which the start point and end point of the closed trajectory are shifted in an orthogonal direction by using a deflector (see FIG. JP-A-2003-86129 ) or by a method using layered toroidal electric fields (cf. JP-A-2006-12782 ).

Also, another TOFMS based on a similar concept has been developed (cf. PCT / WO / 2005/001878 ). In this device, the trajectory of a multiple reflection TOFMS (see. GB 2080021 ), in which overtaking occurs, zigzagged.

(MALDI technique and delayed Ion extraction)

at The MALDI technique is a procedure that consists of a matrix (for example, a liquid, a crystalline Compound, a metal powder or the like), at the wavelength of the laser light used Absorption band has, with the matrix to mix a sample or dissolve a sample in the matrix, solidify it and to irradiate the matrix with the laser light to the sample evaporate or ionize. At one through the MALDI technique are embodied laser-induced ionization processes the initial generated during ion generation Energies distributed over a wide range. To the energies in terms of time, is merging in most cases used a delayed ion extraction. The delayed Ion extraction is that with a delay of a few hundred nanoseconds with respect to laser irradiation pulsed voltage is applied.

5 shows a diagram illustrating a conventional MALDI ion source with delayed ion extraction. A sample is mixed with and dissolved in a matrix (for example, a liquid, a crystalline compound, a metal powder or the like). The matrix is then solidified and placed on a sample holder. In order to observe the state of the sample are a lens 2 , a mirror 2 and a CCD camera available. About a lens 1 and a mirror 1 Laser light is directed to the sample to vaporize or ionize the sample. The generated ions are passed through to an intermediate electrode 1 as well as a base electrode applied voltages accelerated and fed into the mass analyzer.

Furthermore, in 5 a sequence of steps for measuring the time of flight into a process with ver delayed ion extraction shown. First, there is an intermediate electrode 1 and a sample holder at the same potential Vs. Then, after a delay of a few hundred nanoseconds with respect to the reception of a signal indicating the laser excitation from the laser, the potential Vs at the intermediate electrode 1 at high speed to the potential V ₁ changed to between the sample holder and the intermediate electrode 1 to generate a potential gradient. This accelerates the generated ions. The start time of the measurement of the time of flight is synchronized with the rise time of the pulsed voltage.

(TOFMS with orthogonal acceleration)

The MALDI technology is close to TOFMS since the ions are generated in a pulsed manner. However, include the ionization method for a mass spectrometric Analysis numerous methods of continuous ion generation such as electron impact (EI), chemical ionization (CI), Ionization with electrospray (ESI) and chemical ionization at ambient pressure (APCI). To combine these ionization methods with TOFMS, a TOFMS with orthogonal acceleration was developed.

6 FIG. 12 is a diagram illustrating a TOFMS using orthogonal acceleration. FIG. An ion source that continuously generates ions creates an ion beam that is continuously introduced into an orthogonal accelerator with kinetic energies of tens of eV. In the orthogonal accelerator, in order to accelerate the ions in a direction orthogonal to the direction in which the ions are introduced from the ion source, a pulsed voltage greater than tens of kV is applied.

(TOF / TOF)

An MS / MS device in which two TOFMS devices are tandemly connected is commonly referred to as a TOF / TOF device and is mainly used in a device that uses a MALDI ion source. A prior art TOF / TOF device composed of a linear TOFMS and a reflectron TOFMS is shown in FIG 7 shown. Between them an ion gate for selection of precursor ions is arranged. The focal point of the first TOFMS is located near the ion gate.

There are several types of ion gates. A typical ion gate consists of a parallel plate construction in which two electrodes are arranged opposite each other. Another typical ion gate is the Bradbury-Nielson ion gate, which alternately applies voltages of different polarities to multiple wires. Furthermore, it is proposed as a method for improving the ion selectivity, along the flight axis to arrange two ion gates (s. JP-A-2005-302728 ).

In Some cases may involve precursor ions fragment spontaneously (that is, it is metastable Decays, post-source decay (PSD)). In other cases will be the precursor ions in a collision cell, which before the Reflector field of the first or second TOFMS is arranged, forced fragmented. The following are the advantages and disadvantages of a MALDI-TOF / TOF mass spectrometer described.

advantages

• Advantage 1: It is possible using the MS / MS technique Samples that were ionized with a MALDI technique effectively too measure up.
• Advantage 2: It is one of the few devices capable of producing ions with high collision energy (about 20 keV) to fragment (see Table 1).

disadvantage

• Disadvantage 1: The selectivity with respect to the precursor ion is low.
• Disadvantage 2: The mass resolution and the mass accuracy of the MS2 are low.
• Disadvantage 3: Since the product ions produced by the PSD fragmentation and the product ions generated by the CID fragmentation mixed, the resulting spectrum is complicated and difficult analyze.
• Disadvantage 4: There can only be one kind of precursor ions to be selected.

This leads to unnecessary consumption of the sample.

As will be described later, there are some reports about Method for overcoming the disadvantages 1 and 2. However disadvantages 3 and 4 are fundamental disadvantages the TOF / TOF devices of the prior art and it is therefore difficult to overcome these disadvantages.

(1st problem with the devices after the prior art)

A first problem with the prior art devices is that the precursor ion selectivity is low. The precursor ion selectivity is related to the effective time of flight of the TOF1 and to the performance of the ion gate. Often, the first MS in the prior art TOF / TOF devices is a linear TOFMS, as previously mentioned. As a result, the effective flight distance is about 0.5 m. It is necessary to consider the performance of the ion gate in spatial and temporal terms. 8th shows in the case where the effective travel distance of the TOF1 is set to 0.5 m, the differences of the times to which ions with a m / z value of 999, 1,000 and 1,001 as well as kinetic energies of 20.0 kV and 19.9 kV arrives at positions 0.3 m before and after the ion focus of the TOF1 with respect to the time at which ions with a m / z value of 1,000 and a kinetic energy of 20.0 kV arrive at the same positions. The focal point (0 m on the horizontal axis) is the focal point of the TOF1. It can be seen that ions of the same m / z value but different kinetic energies arrive at the same time.

Out It can be seen from the figure that ions which vary in m / z by one Unit differ, at the positions 0.1 m in front and behind the Focus point have no time difference and thus overlap with each other. This means that it does not matter how short the response time of the ion gate is impossible to separate these ions. Furthermore, at positions within 0.1 m before and after the focal point where there is no overlap, the Time difference about 5 ns per m / z. About that In addition, the spatial difference is only approximate 0.5 mm. Consequently, the ions can not be separated. As a result, the condition that the ion gate comes close results at the focal point of the TOF1. Furthermore results the precursor selectivity of the TOF / TOF about two units around m / z.

(2nd problem with devices after the prior art)

One second problem with the devices of the prior art is that the mass resolution and the mass accuracy MS2 is low. The reason for the low mass resolution and mass accuracy of the MS2 is closely related to problem 1 and the high-energy CID, which is an advantage of the TOF / TOF device is connected.

The kinetic energy U _{pro of} a product ion generated by collision-induced dissociation can be represented as Upro = (m / M pre ) × U pre where U _{pre is} the kinetic energy of the precursor ion, M _{pre is} the mass of the precursor ion and m is the mass of the product ion. For example, if the acceleration energy is 20 kV and the valency of the precursor ion 1 is, the kinetic energy U _pre 20 kV and consequently the fragmentation generates in principle product ions with kinetic energies between 0 and 20 keV.

In this connection, some methods have been proposed to combine ions with a wide range of kinetic energies. In a method (cf. U.S. Patent No. 6,441,369 ) suppresses the distribution of kinetic energies by decelerating, fragmenting and accelerating. In another method (s. U.S. Patent No. 6,300,627 ), the potential is quickly changed to a certain range after fragmentation and the ions are then accelerated again. In another method (s. U.S. Patent No. 4,625,112 ) uses a reflectron field with a gradient of the electric field. In yet another method (see. JP-A-2006-196216 ), a renewed acceleration is combined with an offset parabolic ion mirror (a reflectron field formed by a linear electric field and a parabolic electric field). However, these methods make it difficult to combine all the ions that have a large range of kinetic energies. Generally speaking, MS / MS measurements result in lower mass resolving power than MS measurements using a reflectron TOFMS.

The Resolving power is provided by the design of the TOF / TOF device deteriorated. As previously in the context of the prior art A TOFMS is based on the assumption that all ions at the time of starting the measurement with the exception of an initial distribution at the same Position. However, if TOFMS devices are tandem not all ions are in an identical starting position, since ions with different m / z are separated by the TOF1 and due to poor precursor ion selectivity several ions with different m / z values into the second TOFMS be introduced. As a result, the mass resolution deteriorates and the mass accuracy of the TOF2.

(3rd problem with devices after the prior art)

One third problem with the devices of the prior art is that the results of an MS / MS measurement are complex. The main advantage of a TOF / TOF device is that It is one of the few devices that has a high energy level CID enabled. However, it is known that in the MALDI technique usually metastable decays (PSD, post-source decay) take place. The fragmentation pathways of a PSD process are close to the Paths of a low-energy CID. It continues to be in the prior art TOF / TOF devices TOF1 around a linear TOFMS and it is therefore impossible Separate PSD ions. Consequently, the MS / MS measurement results reflect at the same time fragmentations due to CID and PSD again. in the The result, as shown in problem 2, is the MS / MS spectrum very complex due to the low resolution of the MS2. Consequently, it is difficult to analyze the spectrum.

(4th problem with devices after the prior art)

A fourth problem with the prior art devices is that during an MS / MS measurement, it is only possible to measure the fragmentation path of a single precursor ion. Table 2 shows the results of calculations of the relationship between the masses of the first precursor ions and the mass of a precursor ion that can next be selected if multiple precursor ions are measured in MS / MS measurements using a TOF / TOF Apparatus in which a linear TOFMS and a reflectron TOFMS are combined in the prior art. L1 is the effective flight path of the first (linear) TOFMS. L2 is the effective flight path of the second (reflectron) TOFMS. In the calculation, L1 / L2 was set to 0.5. Table 2 Mass of the first selected precursor ion Mass of the precursor ion that can be selected next if L1 / L2 = 0.5 500 4500 600 5400 700 6300 800 7200 900 8100 1000 9000 1100 9900 1200 10,800 1300 11,700 1400 12,600 1500 13,500

As from Table 2, the mass difference is between the first selected precursor ion and the next selected precursor ion big. It was actually impossible to have multiple precursor ions in a measurement. This means that the sample is unnecessarily consumed, except for the selected Precursor ions suppress all ions were.

Summary of the invention

In view of the foregoing, it is an object of the present invention to provide a new TOF / TOF Ge It is also desirable to provide a solution which overcomes the problem with the prior art TOF / TOF devices while taking advantage of the prior art TOF / TOF device. It is a further object of the invention to provide a method that is implemented in this new TOF / TOF device.

A Embodiment of the present invention provides Tandem time-of-flight mass spectrometer with: an ion source for ionization a sample, accelerating means for accelerating the ions generated in a pulsed manner, a first Time of Flight Mass Spectrometer (TOF), which consists of several electrical sectors and a spiral Trajectory, causing the accelerated ions to spiraling, one in the first TOF mass spectrometer arranged ion gate, which exclusively ions with selects a certain mass-to-charge ratio, a collision cell arranged in the direction of flight to the ion gate, which is filled with gas to the selected ions to fragment, one with respect to the direction of flight the collision cell arranged second time-of-flight mass spectrometer (TOF) of the reflectron type for the analysis of the masses of the fragmented ones Ions and a detector for detecting the ions, the second Have passed through TOF mass spectrometer. The first TOF mass spectrometer met with respect to the direction of flight and one to the direction of flight vertical plane every time ions on the spiral Trajectory perform a round, spatial focusing conditions. The ion gate is within the first TOF mass spectrometer arranged in the spiral trajectory. The by the Ion gates selected ions pass through in the direction of flight after the ion gate arranged electrical sectors and connect into the collision cell.

According to one Feature of the present invention is between the first and the second TOF mass spectrometer arranged a second detector, which are moved into and out of the ion trajectory can.

According to one further feature of the invention, a further detector is arranged, to detect ions that pass through the first TOF mass spectrometer to have. The arranged between this detector and the ion gate electrical sector is provided with a hole to pass through to allow the ions. The collision cell and the second TOF mass spectrometers are arranged such that ions containing the Have passed through hole, enter the collision cell.

The Power supply to the ion passage hole in the electrical Sector comprehensive hierarchical level can be independent be switched off from the other hierarchical levels. Becomes carried out a tandem mass analysis with the first and second TOF-MS, Thus, the power supply to the hierarchical level is turned off and the ions can go through the hole.

According to one Another feature of the invention is the time at which the power supply is turned off, the time to the precursor ions pass.

According to one Still another feature of the invention is in the same free space arranged on the spiral trajectory two ion gates. A voltage for turning on and off the gates is from the same Energy supply provided.

According to one additional feature of the invention are at the same angular position at different vacancies on the spiral Trajectory two ion gates arranged. A voltage for switching on and off the gate is provided by the same power supply.

According to one Another feature of the invention are in several places on the same Angular position at different vacancies on the spiral Trajectory multiple ion gates arranged.

After this the ions have passed through all the ion gates, the ions become to it caused to go through electrical sectors.

According to one additional feature of the invention is in the direction of flight in front of the collision cell a deceleration area and in the direction of flight to the collision cell arranged a re-acceleration area.

According to one additional feature of the invention is the reflectron field of the second TOF-MS with an ion mirror a curved potential distribution.

According to an additional feature of the invention is seen in the direction of flight after Kollisionszel le an area for re-acceleration provided. The reflectron field of the second TOF-MS is an ion mirror with a potential distribution in the form of a tandem-like combination of a straight line and a parabolic line.

at a reflectron field formed by a plurality of electrodes, if the voltages applied to the electrodes by means of two power supplies different polarities and an adjacent electrode shared resistance to be shared, one between the electrode located at the ends of the two electrodes at ground potential placed. The two power supplies are connected to the electrodes connected at the opposite ends. The polarities the two power supplies are on the different Sides of the earth potential.

According to one additional feature of the invention, the sample in the Ion source by irradiation on a conductive sample holder arranged sample ionized with laser light.

According to one additional feature of the invention, the sample in the Sample source ionized by a MALDI technique.

According to one additional feature of the invention are the ions with accelerated delayed ion extraction.

According to one Another feature of the invention is in the acceleration means for accelerating the ions in a pulsed manner from the ion source out to a method with orthogonal acceleration, in which ions generated in the continuous ion source with low Guided energies and accelerates the ions in a pulsed manner become.

One Method for tandem time-of-flight mass spectrometry according to Embodiment of the present invention will be carried out MS / MS measurements with selection of multiple precursor ions in a time-of-flight measurement using the previously described Tandem time-of-flight mass spectrometer implemented.

According to one additional feature of the invention is all of the multiple precursor ions are all monoisotopic Ions.

The Tandem time-of-flight mass spectrometer according to a Embodiment of the present invention comprises: a Ion source for ionization of a sample, accelerator for Accelerating the ions in a pulsed manner, a first time-of-flight mass spectrometer (TOF), which consists of several electrical sectors and a spiral Trajectory, causing the accelerated ions to spiraling, one in the first TOF mass spectrometer arranged ion gate, which exclusively ions with selects a certain mass-to-charge ratio, one in the direction of flight after the ion gate arranged collision cell, the fragmentation of the selected ions with a Gas is filled, a second time-of-flight mass spectrometer (TOF) of the reflectron type in the direction of flight after the collision cell is arranged and analyzed the masses of fragmented ions, and a detector for detecting the ions comprising the second TOF mass spectrometer have gone through. The first TOF mass spectrometer met with respect to the direction of flight and one perpendicular to the direction of flight arranged plane at each circulation, the ions on the spiral Trajectory traverse, spatial focusing conditions. The ion gate is within the first TOF mass spectrometer arranged on the spiral trajectory. The electrical Sectors are arranged in the direction of flight to the ion gate. consequently can provide a new tandem time-of-flight mass spectrometer That will be the benefits of a tandem time-of-flight mass spectrometer uses the state of the art and overcomes the disadvantages.

at the method of tandem time-of-flight mass spectrometry according to a Embodiment of the invention, MS / MS measurements are performed taking several precursor ions in a time-of-flight measurement Using the tandem time-of-flight mass spectrometer selected become. Consequently, a new method for tandem time-of-flight mass spectrometry can be used be provided that the advantages of the method of tandem time-of-flight mass spectrometry uses the state of the art and overcomes the disadvantages.

These and other objects and advantages of the present invention from the following description.

Brief description of the figures

 It demonstrate:

1 a diagram illustrating a prior art MS / MS device;

2 a diagram illustrating a MS / MS measurement according to the prior art;

3 a diagram illustrating a linear TOFMS device according to the prior art;

4 a diagram illustrating a prior art reflectron TOFMS device;

5 a diagram of a prior art MALDI ion source;

6 a diagram of a TOFMS device with orthogonal acceleration according to the prior art;

7 a diagram of a TOF / TOF device according to the prior art;

8th Graphs illustrating an example of the precursor ion selectivity obtained in the prior art;

9 a diagram illustrating a TOF / TOF device according to an embodiment of the present invention;

10 Graphs illustrating an example of the precursor ion selectivity obtained according to the present invention;

11 a mass spectrum of angiotensin I including the isotopic peaks and a monoisotopic peak;

12 a diagram of a TOF / TOF device according to another embodiment of the invention;

13 a diagram of a TOF / TOF device according to another embodiment of the invention;

14 a diagram of an ion gate according to an embodiment of the invention;

15 a diagram illustrating MS / MS measurements in which multiple precursor ions are selected; and

16 a diagram illustrating both a reflectron field generated according to an embodiment and a reflectron field generated according to the prior art.

Detailed description the invention

in the The following will be the preferred ones with reference to the drawings Embodiments of the present invention are described. In the following description, the invention will be directed to a mass spectrometer apparatus which includes a first TOF-MS, which is a TOF-MS with a spiral Trajectory formed by four electrical sectors becomes. Similarly, a device with multiple Reflection and a zigzag trajectory used become. Further, in the following description, in the ion source a MALDI process is used. In addition to similar Way a method with orthogonal acceleration in the case of Use of a continuous ion source can be used. Further, the second TOF-MS uses in the following description a new acceleration and a staggered parabolic ion mirror. Instead, other methods of merging may be used kinetic energies as well as other ion mirrors are used.

First embodiment

9 shows a tandem time-of-flight mass spectrometer according to a first embodiment of the present invention. In 9 (a) the device is shown in the Z-direction. In (b) the device is in the in (a) indicated by arrows direction (Y-direction) shown. The spectrometer includes a MALDI ion source 11 , electrical sectors 12 to 15 which are stacked in the Z-direction to form an 8-shaped spiral trajectory, an ion gate 16 for selecting precursor ions, a collision cell 17 for fragmentation of ions, an area 18 for re-accelerating ions disposed between a helical trajectory TOF MS (hereinafter referred to as first TOF-MS) and a reflectron TOF-MS (hereinafter referred to as second TOF-MS) and a constant or pulsed voltage used, a reflectron field 19 that in the collision cell 17 fragmented ions are supplied, as well as a detector 20 for detecting the of the reflectron field 19 reflected ions. In this embodiment, the reflectron field is formed by an offset parabolic ion mirror. In the direction of flight in front of the collision cell 17 For example, a region for decelerating ions may be provided.

The most important feature of the present embodiment is that some of the electrical sectors travel in the direction of the ion gate 16 are arranged and operated as a mass filter, to prevent product ions that after passing through the ion gate 16 produced by a spontaneous fragmentation of ions entering the second TOF-MS. The operation of the device constructed in this way will be described below.

First, the constituents of a sample are ionized in the MALDI ion source. The resulting ions are accelerated by delayed ion extraction. The ion optics of the first TOF-MS are designed such that spatial focusing conditions with respect to the flight direction and a direction perpendicular to the flight direction are met each time the ions circulate on the 8-shaped helical trajectory. The second TOF-MS has the possibility of focusing the kinetic energy. A focal point formed by the delayed ion extraction 1 will be in the starting point of the area 18 to accelerate again. The ions of the sample are separated as they pass through the first TOF-MS and the second TOF-MS according to their mass-to-charge ratios. In the case of MS measurements, the separated ions are from the detector 20 detected.

As previously described, must be in the TOF / TOF according to the prior art Ion gate can be arranged near this focal point. About that In addition, the precursor ion selectivity is very high low. In contrast, in one embodiment As the first TOF-MS of the present invention, a TOF-MS with helical Trajectory used. Consequently, the effective flight distance can be up be extended to the ion gate. Consequently, can be independent from the focal point a high precursor ion selectivity be achieved.

10 shows in a case where the effective flight distance (distance to F1 + length of the circular trajectory) to the focal point is set to 10 m, the differences in the arrival times of ions with m / z values of 999, 1,000 and 1,001 as well as kinetic energies of 20.0 keV and 19.9 keV at positions located 0.3 m before and after the ion focus of the first TOF-MS, and arrival times of ions with m / z values of 1000 and kinetic energy of 20.0 kV. At the position of the ion gate, ion packets enter the same state as at the position of F2. Assuming that the difference between the distance to F1 and the distance to F2 is about 0.2 to 0.3 m, the ion gate is within the range of -0.2 m to -0.3 m in the figure arranged. How out 10 becomes apparent, even at a distance of 0.2 m from the focal point F1 ions that differ by one m / z unit, well separated spatially and temporally. Consequently, high precursor ion selectivity can be achieved. Since the deviations in the position and the angle which allow ions to pass through an electric sector are very limited, a higher precursor ion selectivity than with a simple ion gate can be obtained by using the aforementioned ion gate 16 in the direction of flight in front of the electrical sector.

The selected precursor ions enter the collision cell 17 and collide with the gas introduced into the cell, inducing fragmentation. As a result, product ions are generated. At this time, the electric sectors constituting the first TOF-MS have the function of a filter of the kinetic energy, and hence ions generated during the passage of the first TOF-MS by fragmentation due to a PSD process can be filtered out. That is, one can obtain a mass spectrum consisting solely of fragmentation ions through high energy CID.

All product ions and precursor ions are in the range 18 accelerated again for re-acceleration by the constant voltage or the pulsed voltage. The kinetic energies are brought together and the ions are then expressed according to the m / z value in the second TOF-MS, that from the staggered parabolic ion mirror 19 , in front of and behind the mirror 19 arranged free areas as well as the detector 20 exists, separated. The separated ions are from the detector 20 detected.

It It is observed that mass spectra are different from normal organic ones Substances are derived containing isotope peaks by Isotopes of the constituent elements are formed. Under these Isotopic peaks become the peaks with the minimum mass, that is Ions made exclusively of isotopes with the least Mass with regard to constituent elements exist as monoisotopic Called ions. Peaks indicating monoisotopic ions become referred to as monoisotopic peaks.

11 is a mass spectrum containing isotopic peaks and a monoisotopic peak of angiotensin I (C ₆₂ H ₉₀ N ₁₇ O ₁₄ ⁺ ). The advantage of high precursor ion selectivity becomes apparent when monoisotopic ions consisting exclusively of isotopes with the minimum mass number of the constituent constituents are selected. This means that even product ions are composed of isotopes with the lowest masses and consequently only one peak appears for a compound. Consequently, a complex MS / MS structure of complex CID fragmentation ions can be simplified.

Becomes using a MALDI process, one obtains in MS measurements a high number of ions derived from the matrix at m / z <500. The above Ion gate mentioned can also be used with ions high intensity, such as derived from the matrix Ions, to eliminate.

Second embodiment

The second embodiment is similar to the first embodiment except that, as in FIG 12 shown, additionally a detector 21 is present for MS measurements. Usually, the diameter of the openings for the ion exit and the ion input of the collision cell 17 about 1 mm to ensure tightness. Consequently, there is a possibility that a detection of ions that the collision cell 17 in the context of MS measurements in terms of sensitivity is disadvantageous. Furthermore, as described above, the mass dependency of the mass resolution in MS measurements can be reduced by shortening the distance between the sample holder and the focal point used in delayed ion extraction. For these reasons, indeed, both in MS measurements and in MS / MS measurements, an improvement in the data can be achieved by changing the focal point used in delayed ion extraction.

First, the compounds of a sample are ionized in the MALDI ion source. The resulting ions are accelerated by delayed ion extraction. The ion optics of the first TOF-MS are designed such that spatial focusing conditions with respect to the direction of flight and a direction perpendicular to the direction of flight are met each time the ions circulate on the 8-shaped spiral trajectory. This means that the focal point formed by the delayed ion extraction can be placed in position F2, that of the position of the detector 21 in the last round corresponds to the spiral trajectory. The ions of the sample are separated according to the mass-to-charge ratio by the first helical trajectory TOF MS. In the case of MS measurements, the separated ions are from the detector 21 detected. When a MALDI process is used, a large amount of matrix ions is often generated. High-intensity ions such as matrix ions can pass through the spiral trajectory in front of the detector 21 arranged ion gate 16 be eliminated.

In the case of MS / MS measurements, the detector becomes 21 moved out of the ion trajectory and the ions can pass. The measurement conditions are set so that the focal point formed by the delayed ion extraction is at the position F2, around the starting point of the range 18 to re-accelerate, that is, to focus on the starting point of the second TOF-MS. As shown in the first embodiment, ions differing only by an m / z unit are spatially and temporally good near positions spaced in the narrow range of 0.2 to 0.3 m from the focal point F1 separated. By arranging the ion gate in these positions, high precursor ion selectivity can be achieved.

The selected precursor ions enter the collision cell 17 and collide with the gas introduced into the cell, resulting in fragmentation. As a result, product ions are generated. At this time, the electric sectors constituting the first TOF-MS have the function of a filter with respect to the kinetic energy, and thus ions generated during the passage of the first TOF-MS by fragmentation due to a PSD process can be eliminated. This means that one can obtain a mass spectrum consisting exclusively of fragmentation ions through high energy there is a CID.

All product ions and precursor ions are in the range 18 accelerated again for re-acceleration by the constant voltage or the pulsed voltage. The kinetic energies are brought together and then the ions become the m / z value in the second TOF-MS resulting from the staggered parabolic ionic mirror 19 , in front of and behind the mirror 19 arranged free spaces as well as the detector 20 exists, separated. The separated ions are from the detector 20 detected.

Third embodiment

The present embodiment is a partial modification of the second embodiment as shown in FIG 13 is shown. In the present embodiment, in an electrical sector, which is in the direction of flight in front of the circular circulation, in which the detector 21 is arranged, and after the circular circulation, in which the ion gate 16 is arranged, an ion passage hole 22 educated. The collision cell 17 , the area 18 for re-acceleration, the offset parabolic ionic mirror 19 as well as the detector 20 are arranged in a straight line representing an extension of the trajectory extending straight from the ion passage hole.

In the case of MS measurements is applied to the electrical sector, which is the ion passage hole 22 has applied a voltage. The ions are caused to orbit on the helical trajectory without any leakage of ions through the via 22 is possible. In the case of MS / MS measurements, the electric field generated by the electrical sector must be turned off to that of the ion gate 16 to allow selected ions through the ion passage hole 22 to step. If all of the hierarchical levels of the stacked electrical sectors forming the 8-shaped helical trajectory are electrically interconnected and the voltages are provided by the same power supply, the voltages can be turned off only at the time the selected precursor ions fly past. If the hierarchical level with the ion passage hole is electrically disconnected from the other hierarchical levels, the operation mode can be switched between an MS measurement mode and a MS / MS measurement mode by using a switch for turning on and off the voltage in the aforementioned hierarchical level is provided.

Fourth embodiment

The present embodiment is similar to the first to third embodiments, however, as shown in FIG 14 shown, the ion gate has been modified. The apparatus according to the first embodiment has the capability of precursor ion selection by separation of ions differing by one m / z unit. In order to obtain the smallest possible design of the device and a higher selectivity, it is also necessary to shorten the claim time of the ion gate. As previously described in connection with the prior art, in this case there is a method using two ion gates. For example, ions with m / z values that are smaller than the m / z values of the precursor ions to be selected are eliminated by the ion gate closer to the MALDI ion source, while ions with m / z values greater than the m / z values of the precursor ions are eliminated by the ion gate located closer to the detector.

As described in the first to third embodiments, in the prior art TOF / TOF apparatus, the ion gate must be located near the focal point of the TOF1. In the present embodiment, the position of the ion gate can be chosen relatively freely. Thus, using two ion gates, different arrangement methods can be used. However, extension of the power supply line to the ion gates results in degradation of the response of the ion gates themselves. Considering this point, the ion gates may be arranged in space of the same hierarchical level as in FIG 14 shown. As in 14 (b) As shown, the ion gates may be arranged in relatively close positions to each other in different hierarchical planes. In 14 (c) An ion gate of the Bradbury-Nielson type spans different hierarchical levels. The ion gate is an integral structure. Of course, ion gates with parallel plates can also be arranged in a similar manner.

Fifth embodiment

The present embodiment provides a method for selecting multiple precursor ions in Mes using the same laser irradiation to reduce the consumption of a sample. The present embodiment is a modification of the first embodiment. The second to fourth embodiments can be similarly modified.

First The compounds of a sample are ionized in the MALDI ion source. The resulting ions are accelerated by a pulsed voltage. The compounds of the sample are ionized into sample ions transformed. In the first TOF-MS, the sample ions are determined according to the Mass-to-charge ratio separated. The sample ions, the have passed through the first TOF-MS through the ion gate selected. The selected precursor ions enter the collision cell and collide with the in the Cell-filled gas, thereby inducing fragmentation becomes. As a result, product ions are generated. The precursor ions and the product ions are detected by the detector.

Next, referring to 15 described the MS / MS mode in which multiple precursor ions are selected. For purposes of illustration, it is assumed that in the MALDI ion source 7 sample-derived precursor ions Pre1 to Pre7 are present. Each ion has a valence of 1. The lower numbered ions have lower masses. The ions are accelerated by the MALDI ion source and separated by the first TOF-MS in terms of mass. Then come the ions, as in 15 (a) shown, in order from the lightest to the heaviest ion on the ion gate.

T _{n, IG} is the arrival time of the respective precursor ion PreN at the ion gate. First, an MS / MS measurement in which a precursor ion Pre4 is selected will be described. If only Pre4 is selected by the ion gate and fed into the collision cell, two cases can occur: in one case, fragmentation is induced and product ions are generated; otherwise, precursor ions undergo the collision cell intact without fragmentation. If fragmentation occurs, the kinetic energy U _{pre4 of} the precursor ion during fragmentation is distributed proportionally to the masses of product ions. That is, the kinetic energy U _{pro of} the product ion is _equal to m / M _pre4 × U _pre4 (where m is the mass of the product ion).

Subsequently, the precursor ions and the product ions are supplied to the second TOF MS. In the reflectron field of the reflectron TOF-MS, ions with smaller kinetic energies rotate and reach the detector earlier. As a result, the precursor ions arrive last at the detector. Let T _{N, D} be the arrival time of the respective precursor ion PreN at the detector. This means that in an MS / MS spectrum obtained when Pre4 is selected, the interval from T _{4, IG} to T _{4, D} can be measured.

On This way, the range of flight times required for MS / MS measurements of precursor ions is needed, respectively easy way to be calculated. It can be seen that if the time-of-flight ranges do not interfere with each other, multiple MS / MS measurements can be performed in the same time of flight measurement.

Around To achieve these circumstances, the interval should be between the flight times of precursor ions on the ion gate larger as the time of flight required for MS / MS measurements be. For this purpose, it is necessary to the ratio the effective distance L1 in the first TOF-MS for the effective route L2 in the second TOF-MS (ie L1 / L2) increase. A TOF MS with a spiral trajectory can be an effective flight path achieve that about 10 times bigger is, as the effective flight path of a reflectron TOF-MS after the state of the art. Consequently, an MS / MS measurement is performed in which several precursor ions selected in the same time of flight measurement be made possible by using a TOF-MS with spiral Trajectory and a reflectron TOF-MS combined.

In the following, this discussion will be carried out more quantitatively. Table 3 shows computational results for the relationship between the mass of the first precursor ion and the mass of the precursor ion that can be selected next for different values of L1 / L2 and different mass values during MS / MS measurements in which multiple precursor ions are selected as the first selected precursor ion. Table 3 Mass of the first selected precursor ion Mass of the precursor ion that can be selected next L1 / L2 = 10 L1 / L2 = 5 L1 / L2 = 0.5 500 605 720 4500 600 726 864 5400 700 847 1008 6,300 800 968 1152 7200 900 1089 1296 8100 1000 1210 1440 9000 1100 1331 1584 9900 1200 1452 1728 10,800 1300 1573 1872 11,700 1400 1694 2016 12,600 1500 1815 2160 13,500

at The present invention may be the value of the effective flight path L1 of the first TOF-MS by the distance of the circular Orbit of the TOF-MS with spiral orbit as well the number of rounds are chosen relatively freely. Table 3 shows cases where L1 / L2 is 5 and 10, respectively. In the case of the prior art TOF-MS device L2 in many cases longer and the L1 / L2 values are approximately less than 0.5. From Table 3 becomes it can be seen that in the case of a device according to the state of Technique of the mass difference between the first selected Precursor ion and the next selectable Precursor ion is so large that it is essentially impossible to select multiple precursor ions. In contrast, in the case of the present device the mass difference between the first selected Precursor ion and the next selectable Precursor ion in the range of a few hundred, so that sufficient multiple precursor ions can be selected.

Sixth embodiment

Often, an ion mirror, as in 16 (a) shown, an array of several ten perforated electrodes. A power supply is applied via the electrode arrangement. Resistance division supplies the intermediate electrodes with voltage. In many cases, the voltages at the opposite ends of the ion mirror have an opposite polarity and lie on opposite sides with respect to the ground potential. The power supplies suffer from voltage fluctuations or a time drift due to temperature changes. The voltage applied to the electrodes has a buzz or a temporal drift, as described above. Changes in the power supplies connected at the opposite ends add up. In the present embodiment, as in 16 (b) In a case where the potentials are opposite in polarity and located on opposite sides of the ground potential, the effects of changes of the power supplies are suppressed by placing an electrode at ground potential. The accuracy of the power supplies for the electrodes can be improved. This means that the accuracy of the time of flight during the measurements can be improved.

The The present invention can be widely applied to tandem MS measurements be applied, which carried out with time-of-flight mass spectrometers become.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• JP 2000-243345 A [0014]
• - JP 2003-86129 A [0014]
• - JP 2006-12782A [0014]
• WO 2005/001878 [0015]
• GB 2080021 [0015]
• - JP 2005-302728 A [0022]
• - US 6441369 [0030]
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Cited non-patent literature

• M. Toyoda, D. Okumura, M. Ishihara and I. Katakuse, J. Mass Spectrom., 2003, 38, pp. 1125-1142 [0012]

Claims (19)

Tandem time-of-flight mass spectrometer comprising: - one Ion source for ionizing a sample; - accelerator for accelerating the generated ions in a pulsed manner; - one first time of flight mass spectrometer (TOF-MS) with a spiral Trajectory, which consists of several electrical sectors, where the first TOF-MS causes the accelerated ions to to move in a spiral; - one inside of the first TOF-MS arranged ion gate exclusively Selecting ions with certain mass-to-charge ratios; - one arranged in the direction of flight to the ion gate and for fragmentation the selected ions filled with a gas Collision cell; A second time-of-flight mass spectrometer (TOF-MS) of the reflectron-type, wherein the second TOF-MS in the direction of flight is arranged after the collision cell and the second TOF-MS the Masses of fragmented ions analyzed; - one Detector for detecting the ions passing through the second TOF MS to have; wherein the first TOF-MS on each revolution of the ions the spiral trajectory spatial focusing conditions with respect to a direction of flight and a direction perpendicular to the direction of flight Level met and the ion gate being on the spiral Trajectory of the first TOF MS is arranged and that of the ion gate selected ions in the direction of flight to the ion gate through arranged electrical sectors and into the collision cell enter. Tandem time-of-flight mass spectrometer according to claim 1, wherein between the first TOF-MS and the second TOF-MS another Detector is placed in the ion trajectory and out This can be moved out. Tandem time-of-flight mass spectrometer according to claim 1, further comprising a detector for detecting ions containing the have passed through the first TOF MS as well as in between the detector and the ionic gate located electrical sectors holes are present, which allow passage of ions, wherein the collision cell and the second TOF-MS are arranged such that the ions that have passed through the holes in the Collision cell occur. Tandem time-of-flight mass spectrometer according to claim 3, the energy supply of a hierarchical level, which is the Ion passage hole in the electric sector with the Ionendurchgansloch includes, shut off regardless of other hierarchical levels and being in a case where a tandem mass analysis performed with the first and second TOF-MS, the power supply to the hierarchical level is switched off and allowing ions to pass through the hole. Tandem time-of-flight mass spectrometer according to claim 4, wherein a time when the power supply is turned off , the timing of the precursor ions passing by is. Tandem time-of-flight mass spectrometer according to claim 1, being at the same vacancy on the spiral Trajectory two ion gates are arranged and where the voltages for turning on and off the gates of the same power supply to be provided. Tandem time-of-flight mass spectrometer according to claim 1, wherein at different vacancies, but in the same angular position arranged on the spiral trajectory two ion gates are and where the voltages for turning on and off the gate provided by the same power supply. Tandem time-of-flight mass spectrometer according to claim 1, wherein at different free locations, but in the same angular positions arranged on the spiral trajectory multiple ion gates are. Tandem time-of-flight mass spectrometer according to claim 8, wherein the ions after passing through all ion gates through the electrical sectors are guided. Tandem time-of-flight mass spectrometer according to claim 1, wherein in the direction of flight in front of the collision cell a braking area is arranged and wherein in the direction of flight to the collision cell an area for re-acceleration is arranged. Tandem time-of-flight mass spectrometer according to claim 1, wherein the reflectron field of the second TOF-MS is a Ion mirror with a curved potential distribution is. Tandem time-of-flight mass spectrometer according to claim 1, wherein in the direction of flight after the collision cell, an area for re-acceleration is arranged and wherein it is in the Reflectron field of the second TOF-MS is an ion mirror, the one potential distribution in the form of a tandem arranged Combination of a straight line and a parabolic line has. Tandem time-of-flight mass spectrometer according to claim 1, in which (A) of a plurality of electrodes a Reflektronfeld is produced, (B) with two electrodes at both ends two Power supplies are connected, the polarities on opposite Have sides of the earth potential, (C) adjacent electrodes are connected by a voltage dividing resistor and (D) in a case where the plurality of electrodes over the Voltage divider resistors of two power supplies be supplied to divided voltages, an electrode, the arranged between the two electrodes at the two ends, at ground potential. Tandem time-of-flight mass spectrometer according to claim 1, wherein the sample in the ion source by irradiating on a conductive sample holder arranged sample ionized with laser light becomes. Tandem time-of-flight mass spectrometer according to claim 14, wherein the sample in the ion source by a MALDI process is ionized. Tandem time-of-flight mass spectrometer according to claim 15, wherein the means for accelerating the ions to is a delayed ion extraction. Tandem time-of-flight mass spectrometer according to claim 1, wherein the ion source is a continuous ion source and wherein the acceleration means for accelerating the Ions out of the ion source in a pulsed manner by one method with orthogonal acceleration, which consists of the fact that the ions generated by the continuous ion source with low Energies are conducted and the ions in a pulsed manner be accelerated. Method for tandem time-of-flight mass spectrometry, comprising the steps of: - Performing a time-of-flight MS measurement using a tandem time-of-flight mass spectrometer Claim 1; - Selecting multiple precursor ions and - Performing an MS / MS measurement. Tandem time-of-flight mass spectrometry method according to claim 18, wherein the plurality of precursor ions all are monoisotopic ions.